1. Field of the Invention
The present invention relates generally to a method of controlling operation of an injection molding system for producing a desired product such as a compact disk (CD), a digital video disk (DVD), or the like, wherein the product is molded by an injection molding machine and is further processed in the following or subsequent step or steps. More particularly, the present invention is concerned with such a method of controlling operation of an injection molding system, which method permits the injection molding system to resume its operation in a short time, with a minimized loss of manufacture, when the subsequent step or steps is/are troubled.
2. Description of the Related Art
There is known an injection molding system in which a desired product is molded by an injection molding machine and is then processed in the subsequent step or steps. In this conventional molding system, the injection molding machine is arranged to be held in its normal operation mode so as to continue its injection molding operation, even where the subsequent step(s) is/are unavailable for processing the molded products. There is also known another injection molding system in which a plurality of injection molding machines produce components of a desired product, respectively, and these components are transported to the subsequent common step(s) so as to be assembled into the desired product. In this conventional molding system, each of the injection molding machines is also arranged to be held in its normal operation mode so as to continue its injection molding operation, even in the case where the plurality of injection molding machines are not simultaneously started so that the molded components cannot be assembled in the subsequent step(s).
In order to solve the above-described problems, it can be envisioned a method of once stopping the injection molding machine. However, this method is not practical, since the method causes undesirable decrease in temperature of a mold of the injection molding machine and accordingly causes variation of temperature of a mass of molten or plasticized resin material stored in a heating cylinder of the injection molding machine, thereby requiring a relatively long interval before resuming the injection molding operation of the injection molding machine. This means that the injection molding machine of the conventional injection molding systems is necessarily required to be held in its normal operating condition, even if the subsequent or other step(s) becomes unavailable. In this condition, an injection molding system for producing a CD, for example, may produce a stack of a larger number of molded disk substrates to be processed in the subsequent step(s), requiring a separate storage of these molded disk substrate and a re-execution of only the subsequent step(s) with respect to these stored molded disk substrates. Thus, the conventional injection molding system for producing the CD suffers from extremely low production efficiency.
Further, in a conventional injection molding system for producing a DVD or the like, for example, two injection molding machines produce respective component disks which are transferred to the subsequent common step(s) to provide a bonded composite disk used as the DVD. In this case, the two injection molding machines are required to substantially simultaneously produce the component disks to be bonded together into the bonded composite disk. If this requirement is not satisfied, the resultant bonded composite disk may suffer from occurrence of defects such as bending or buckling thereon. When one of the two injection molding machines does not operate due to a delay in its starting operation, or a stop of its operation, the other injection molding machine is still held in its normal operation mode so as to produce the component disks. Thus, the component disks molded by the other injection molding machine cannot be utilized for producing the bonded composite disks, until the operation of the one injection molding machine is started or resumed, resulting in undesirable disposal of these molded component disks.
The present invention has been developed in view of the circumstances described above. It is therefore an object of the present invention to provide a method of controlling operation of an injection molding system, which method permits an improved production efficiency of the injection molding system and allows an injection molding device to resume its operation in a short time, when the subsequent step or steps is/are malfunctioned.
The above-indicated object of the present invention may be achieved according to a principle of this invention which provides a method of controlling operation of injection molding device including at least one injection molding device successively executes an injection molding operation thereof so as to successively produce a molded product, at least one takeout device successively takes out the molded product from the corresponding injection molding device so as to successively transfer the molded product to a subsequent-step part adapted to further process the molded product, and a monitoring device adapted to detect an abnormal operation in the subsequent-step part and generate an abnormal signal upon detection of the abnormal operation, the method comprising the steps of: changing an operation mode of the at least one takeout device so as to transfer the molded disk to a part which is separate from the subsequent-step part, upon generation of the abnormal signal by the monitoring device; and extending a cycle time of the injection molding operation of the at least one injection molding device, upon generation of the abnormal signal by the monitoring device.
Preferably, the extension of the cycle time is executed by controlling a cooling time and/or an intermediate time after a completion of the product-takeout action and before an initiation of the mold closing action, by a suitable timer.